But as the heads of state arrived in Rio yesterday and began addressing one another in high-level meetings, I couldn’t help but feel surprised … and a bit hopeful.

Over the last few years, I have spent a lot of time following countries as they negotiate details of the international agreements on climate and biological diversity (UNFCCC and CBD). Much discussion there focuses on vulnerability, equity, financing, responsibility … all very important issues, which are also at the heart of negotiations here in Rio.

Along those lines, yesterday I was moved by a speech given by President Anote Tong of Kiribati, who spoke of his country being collateral damage in the path of climate change. He asked world leaders: “Are we here to secure the future of each other’s children, or just our own?”

However, Tong then went on to outline what his nation is doing to protect the future for all of us, even while his islands’ people are considering where they will live once their homes are underwater.

A number of other leaders went on in this same vein:

The president of Hungary, János Áder, said: “I call on our common conscience. Because the question marks of 20 years ago have straightened up into exclamation marks. The facts present an alarming picture. Since the end of the eighties, humanity has exceeded biological capacity of the Earth … Our problems are well known. We have knowledge and technology to solve them. We don’t need declaration after declaration. What we need are executable, implementable programs.”

The prime minister of Barbados, Fruendel Stuart, quoted JFK: “Our problems are man-made, therefore they may be solved by man. And man can be as big as he wants. No problem of human destiny is beyond human beings.” Stuart didn’t just share lofty quotes, but went on to say: “It is easy to catalog failed promises of development partners, but I did not come to Rio to remind others of commitments to which they failed to adhere. I am here to tell the world what Barbados has done, is doing and will do to ensure a safe future for current and future generations. Barbados has committed to transform into the most advanced green economy in the Latin American and Caribbean region.”

The South Korean president, Lee Myung-bak, explained that in 2008, South Korea declared low-carbon green growth the new development paradigm for the nation, incorporating all ministries. While acknowledging the country still has some way to go, green industry and technologies are going through rapid development. A new 1,800-kilometer (1,120-mile) riverside bike track has been laid; the era of the electric auto has begun. He also cited the popularity of green buildings and that this Green New Deal has led to job creation for 750,000 people.

I realize that most of these people making solemn speeches about sustainable development are politicians who, even when they feel strongly, must act under a number of constraints which can limit the actions they can take.

But think about it this way — normally, politicians do not say things that don’t reflect what they believe their constituencies also believe and will support. So the words I’m hearing not only represent the hopes of a few leaders, but of all of the people who they represent. And for this reason especially, I have been pleasantly surprised by the number of references to “love” or “happiness” as the basis for a new paradigm of measuring the success of sustainable development.

Some of my colleagues were here in Rio 20 years ago, but I’ve only been following U.N. negotiations for the past four years. However, what I have been hearing over these last few hours feels very different to me from the hours of speeches I have heard in other U.N. meetings.

Yesterday, José Mujica, the president of Uruguay, suggested a new definition of development. “Development should promote human happiness, love, human relationships, relationships between parents and children; these are the fundamental things of life. Life is the most important treasure we have.”